linux-kernel - Re: [PATCH] PM: suspend_device_irqs(): don't disable wakeup IRQs

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Date:	Wed, 6 May 2009 18:18:23 -0700
From:	Arve Hjønnevåg <arve@...roid.com>
To:	Kevin Hilman <khilman@...prootsystems.com>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH] PM: suspend_device_irqs(): don't disable wakeup IRQs

On Wed, May 6, 2009 at 5:16 PM, Kevin Hilman
<khilman@...prootsystems.com> wrote:
> "Rafael J. Wysocki" <rjw@...k.pl> writes:
>
>> On Wednesday 06 May 2009, Kevin Hilman wrote:
>>> Kevin Hilman <khilman@...prootsystems.com> writes:

> There is at least one problem with that which is why Kyuwon Kim added
> the ->disable hook to OMAP's irq_chip.  The problem is with drivers
> that call disable_irq() in their suspend hook, usually done to prevent
> the device from waking the system since on OMAP, any IRQ can be
> configured to wake the system.
>

This does not sound correct. disable_irq_wake should be used for this.
A driver may need to mask its interrupt before suspending but this
should not also disable it as a wakeup source.

> If a driver's suspend hook calls disable_irq() and the system is
> suspended before the lazy disable happens in the next handler, then
> the system will be suspended with that device's IRQ still enabled.
> Without an irq_chip->disable hook, that will result in that device IRQ
> waking up the system if it fires.

The platform suspend code needs to write the wakeup mask into
interrupt controller the before entering suspend.


-- 
Arve Hjønnevåg
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